UK Car Repair Questions? Ask a Mechanic for Answers ASAP
Hi. Purchased a R320cdi 4-matic one month ago. It has turned out to have some electronic (at least I think so) issues. When starting it shows the following "ESP inactive/inoperative", "Pre-Safe inoperative" Speed-Tronic inoperative" and "Tire pressure monitor inoperative". When all of these are shown it will not go into gear, but after shutting engine off, closing/locking doors and restart it mosty will be able to get into gear. At one time it also lit the red emergency display noting "Drive directly to work shop without changing gear". Used mobilio and had it towed. Malfunction said to be from the steering wheel module, but turned out to be the "clock axis module" or something like that inetgrated with the steering wheel module. Car picked up yesterday, worked fine but today at first start attempt same problem with esp, pre-safe etc, but after reset it worked fine. Could it be the battery? My experience with other cars (BMW) tells me that the battery seems fine in the diagnostics tool, but is defect even if it is stated not to be... do you have any ideas... all codes seems to originate from the steering wheel module. Y S /chris
Hello Chris and Welcome! I'm Billy and i will assist you with your inquiry. Feel free to ask if any further info is needed.
The battery, can indeed cause these problems...
However, are you getting the problem only at first start...and then you turn the engine off and then on, and the problem goes away?
did you replace the steering wheel position sensor?
can you get the exact codes you were getting? and are they the same codes now?
Hello Billy. The steering wheel position sensor is replaced, but not the steering wheel column module. I do not have the codes, but the same fault appear when car is started. When shut of and restarted the faults are mostly gone, but I recognize a "build up" of faults that causes the CANBUS to eventually overfill and create a more severe CANproblem...
It will not create problems for the CAN bus. However, the latter communicating all the control units, would cause the fault to appear more than one place (like you are experiencing).
IF you turn the ignition off (before starting the engine), and then on, do you still get the problem?
and was the steering column control module connectors' checked?
Hello Billy. Yes, the faults disappear when car is restarted, but in time i understand that the CANBUS will overflow with faults and cause the CAN to report a more severe problem. The steering wheel position sensor is replaced, but not the steering wheel column module. Also the front right ABS sensor with bearing hub is replaced. One further thing is that when the car is started and the faults appear, the car makes a strange sound, like a cooling fan roaring, but somewhat deeper in tone so to say... the car is equipped with iPod interface...is that a possible cause of the problem (controls are in the steering wheel) It is now disconnected, and since no faults. The faults, though, appears mostly at first start after overnight. When once warm, normally no faults.
I would've discarded the ipod connector as culprit, but since, removing it the problem is no more...then it could cause this, as it is officially connected to the steering control module.
You would need to leave it off for a while, and then install it for a while, to confirm that it is causing this problem.
As for the roar when starting, is it in engine bay?
Also the front right ABS sensor with bearing hub is replaced. One further thing is that when the car is started it makes a strange growling sound like the cooling fan, but somewhat deeper in tone. The car has iPod MB interface installed. Is that a problem? The iPod is disconnected now, and since then no faults. The faults appear when started cold after overnight stop. When engine is warm, normally no problem.
Have not tried to switch off before started, but I've noticed that it needs more preglow then expected for such a modern diesel engine, needing to stop for a couple of seconds before actually starting the engine.
Yes, this is normal....the preglow time is long on newer MB models...
This time is also so the control modules "wake up" and start processing info....
So the pre glow, is just a facade for other operations being tackled.
However, as for the noise you are getting: is it from engine bay?
The roar is in the engine bay, and only when the faults are to appear. When starting it starts to roar, and then, after a couple of seconds, fault lights appear...
Ok... there is a common problem with the alternator pulley clutch, causing problems (loose drive belt), and low power supply, which would cause the warning lights and the fault codes. To make sure if this is your problem, you need to have the bonnet open, and confirm if the fault is coming from the drive belt (specifically the alternator), and replace the alternator clutch pulley accordingly.
If the roar is coming from the engine itself, or from the timing chain, then the first order of business would be checking the engine oil quality and replace if necessary.
Ok, super. Oil level is ok, perhaps somewhat "lowish", but seems to need change even still 10000 km to next service. Low power supply seems possible given my experience with other cars...i e BMW
Thank you for your advice. /chris